I am a paramedic here in Myrtle Beach, I would say if you heard a snoring sound it would be secondary to a partial airway obstruction from his tounqe and other structures in his orophranyx being relaxed by being knocked unconcious. In my experience you would have varying patterns of respirations due to the possibility of a head injury, but the audible noise that you would hear would have to be from some type of structure impedeing proper airflow, causing a snoring sound. If he didn't have a neck injury, a head-tilt chin lift would probably relieve what is causing a "snoring" soud, or a modified jaw-thrust in this case.
(It sounds more less like rapid deep breathing to me, more so than snoring)